1. Field of the invention
The invention concerns ovens for cooking food, comprising a cooking enclosure enclosed by a peripheral wall and a door, with an internal fan for circulating air, rotated by drive motor means, and with means for injecting water into the fan so that the fan blades project the water radially and distribute it onto heating elements disposed at the periphery of the fan.
2. Description of the prior art
Steam ovens of the above kind in which the fan contributes to spraying of the water to be evaporated have been known for a long time. In documents DE 27 47 097 A1 and DE 296 06 655 U1, for example, an internal fan for circulating air is rotated about a horizontal axis and has peripheral blades disposed in a cylinder to aspirate air axially to form an aspirated air flow and to discharge it radially in an air discharge area. Heating elements are disposed at the periphery of the fan and in its depthwise direction in the air discharge area. The water to be evaporated is fed under pressure through a water feed pipe to a spray nozzle in the central flow of aspirated air at the entry of the fan, the nozzle spraying the water axially in the direction of the aspirated air flow. With an arrangement of the above kind a greater part of the sprayed water propagates toward the back of the fan, and is equally distributed onto the corresponding heating elements around all of the periphery of the back of the fan. As a result the heating elements at the periphery of the back of the fan receive a large quantity of water, which they evaporate, whereas the heating elements at the periphery of the inlet portion of the fan receive very little water and remain at a higher temperature. Apart from an unequal distribution of the water to the heating elements, this arrangement necessitates a pressurized water feed and a spray nozzle, a nozzle of this kind tending to become blocked after a period of use because of deposits of impurities or limescale. As a result it must be cleaned fairly frequently, reliability is reduced and steam is produced in an irregular manner.
Solutions to the problem of the spray nozzle becoming blocked have been envisaged in which the water is fed through a pipe under pressure and rotary water spray means are provided in the fan to spray the water radially against the fan blades which then distribute it onto the heating elements. Document EP 0 233 535 A, for example, proposes to feed water under pressure above the fan hub. The water flows over the hub which, by virtue of its rotation, sprays it radially and projects it onto the fan blades. In document EP 0 244 538 A, an inverted cone, with its open smaller end facing the fan inlet and closed at its larger end toward the back of the fan, is fixed to the end of the fan hub. Water is fed into the cone via a pipe and is projected toward the fan blades in the form of a continuous radial film all around the periphery of the cone entry lip. In document EP 0 523 489 A, the water is fed into an open inverted rotating cone from which it escapes toward the fan blades in the form of a radial film at the posterior larger base of the cone. In document DE 41 31 748 A a perforated or ribbed disk is fixed to the end of the fan hub and water is fed onto the anterior face of the disk. Rotation of the disk sprays the water radially toward the fan blades. In document EP 0 640 310 A, water is fed onto a ribbed rotating anterior sphere which sprays the water radially toward the fan blades.
In all these arrangements with rotary water spray means, the water is regularly distributed around the periphery but the water is distributed unevenly along the depth of the fan. As a result only some portions of the heating elements receive a significant quantity of water to be evaporated, other heating element portions receiving only a small portion of the water to be evaporated or none at all. Also, providing the rotating spray parts makes it necessary to modify the structure of the fan and to balance the rotating parts. Manufacture is therefore more complicated.
The problem addressed by the present invention is that of designing a new structure for spraying and distributing water in a steam oven fan that assures an even distribution of the water at the periphery of the fan and in the depthwise direction of the fan, without affecting the balance of the fan itself, and is compatible with a water feed that is not pressurized and therefore without a spray nozzle.
Another object of the invention is to facilitate cleaning of the functional parts of the oven, and in particular the water spraying and distribution parts.